[time-nuts] Symmetricom S200 Antenna Disgnostic and Replacement Recommendation

Bob kb8tq kb8tq at n1k.org
Mon Sep 18 14:17:40 EDT 2017


There is a surprisingly high range of currents pulled by various GPS antennas. In some
cases the wider the voltage range, the higher the current. Some antennas can pull as much as 
150 ma. There are GPSDO’s that trigger over current at 30 ma ….

The “easy” approach is to run the receiver into a DC block and enough of a load resistor
to make the alarm happy. Then run any antenna on the other side fed by a bias tee. The
advantage there is that you don’t have any constraints on the antenna. 


> On Sep 18, 2017, at 2:08 PM, John Laur <johnlaur at gmail.com> wrote:
> All,
> Does anyone have a good recommendation for an inexpensive but effective
> replacement antenna for a Symmetricom/Microsemi S200 or S250? These units
> use a 12V receiver and also have an antenna open/good/short status alarm.
> My antenna recently went to showing open alarm and the receiver will no
> longer lock. I purchased an inexpensive marine-type antenna which appeared
> to be 12V tolerant but triggers the short alarm.
> I know that it is possible that the antenna could be fine like this and the
> alarm could be ignored, but even still I would prefer that the antenna
> current alarm remain functional. Does anyone have a recommendation for an
> effective but inexpensive antenna that tolerates 12V and consumes an
> appropriate amount of current to pacify the alarm? In the event that my
> antenna was damaged by something like a nearby lightning strike that also
> could have damaged the receiver, I would prefer to at least test with an
> appropriate antenna before either risking more damage or deciding to
> attempt a more invasive repair.
> Thanks for any info!
> John Laur K5IT
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